This is what I get when I follow those steps ad try to run
sudo apt install libxp6
Reading package lists... Done
Building dependency tree
Reading state information... Done
Package libxp6 is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source
E: Package 'libxp6' has no installation candidate
The previous steps all seemed to work, but it's the same issue I had encountered trying to install libxp6 on my own. Do you know how to deal with this issue?